The use of mobile devices, and the amount of time that mobile device are in use, continues to increase. As such, power requirements of mobile devices are a significant issue, and the reduction of power consumption in mobile devices is a common design consideration. The power consumption of liquid crystal displays (LCDs) used in many mobile devices typically ranges from 20% to 30% of the total system power. For video images, or frames, that have few or no bright pixels, all pixels of these images can be amplified without introducing any visible artefacts. This procedure increases the perceived contrast and brightness of the corresponding image, the extra brightness of the applied video gain can be compensated by reducing the brightness of the backlight. Gamma correction is used for compensating the dynamic range. However, strong gamma correction leads to substantial loss of contrast and color. One of the well known weakness of LCD's it the capability to reproduce black color. True black gives each color greater definition and creates a far greater number of shades, more depth, and a sharper detail level. By additionally reducing the backlight together with additional gamma correction control an enhancement of the black color is achieved.
Another method of increasing the dynamic range of the display and achieving power savings is automatic brightness control of the backlight based upon ambient light conditions. A sensor measures the ambient light and the backlight is adjusted accordingly. When there is less ambient light the maximum output power of the backlight is reduced, thereby saving power. To save battery life, the backlight is operated at as low a power level as possible. However, this results in insufficient dynamic range in all environments except in very dark environments. Using ambient light compensation, the backlight brightness is changed based on ambient light conditions. This ensures that regardless of ambient light conditions the dynamic range is maintained at a sufficient level.
Conventional light management controllers or LED drivers are only able to effectively handle compensation of either gamma correction or ambient light compensation at a given time. If the light management simultaneously compensates for both gamma correction and ambient light, it is typically achieved by splitting up the compensation into a few discrete steps that result in a poor user experience, higher distortion of the image, and reduced power saving.